Talking about fiscal consolidation is not traditionally the way to a man's heart.

Unless, it seems, that man is Robert Peston. The BBC's business editor became distinctly flustered on air as he discussed remarks made by Christine Lagarde, the glamorous head of the International Monetary Fund, on the UK's austerity measures.

Peston, 52, was on Radio 4's PM programme to analyse the IMF's review of Britain's economy, but was left fumbling for words after gushing about the Frenchwoman's 'silken' charms.

He said Mrs Lagarde had given the Government 'overall about a C or C minus', before adding: 'But she is one of the most charming politicians in the world.'

He continued: 'And in her sort of silken way she...', at which point the show's presenter, Eddie Mair, interrupted with, 'Are you smitten?'

Peston, a married father-of-two, replied: 'I have to say I've met her a few times and she's a very seductive politician, let's put it that way.'

Mair said he should 'try and concentrate on what she said'. The normally exuberant Peston then spluttered: 'Desperately trying to get back to the matter in hand…no she, er, said…I've completely lost my place, I need a glass of water…and you know...'

He recovered his composure enough to deliver the analysis that while Mrs Lagarde, 56, had said things are 'pretty dire', without the Government's deficit cutting plan 'they could have been a hell of a lot worse.'

Mair then played a short recording of Mrs Lagarde, speaking in English, saying: 'When I think back to May 2010 when the UK deficit was at 11 per cent and I try to imagine what the situation would be like today if no such fiscal consolidation programme had been delivered…[she takes a sharp intake of breath]…I shiver.'

Mair, who has long enjoyed a feisty rapport with Peston, a regular on the show, asked: 'It was that bit that got you, wasn't it?' Peston replied: 'It was the frisson at the end, yes.'

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Quite how overcome Peston was when he actually met Mrs Lagarde, who has been married and divorced twice, is not known.

There is little doubt that she cuts an impressive figure, with her silver hair and imposing 5ft 11in height.

She also prides herself on her slim physique, which is toned from regular yoga and swimming.

Already taken: The BBC's business editor Robert Peston with his wife Sian Busby

As a teenager, Mrs Lagarde was a synchronised swimming champion, and now lists scuba diving and gardening among her hobbies.

She has juggled motherhood with an alpha career as a corporate lawyer and French finance minister. In 2011, she became the first female IMF chief when she succeeded Dominique Strauss-Kahn.

The same year Forbes magazine ranked her as the ninth most powerful woman in the world.

Mrs Lagarde married her first husband, a financial analyst called Wilfred Lagarde, in 1982. They had two sons but divorced in 1992. Her second husband was businessman Eachran Gilmour, but that marriage, too, ended in divorce.

'I have to say I've met her a few times and she's a very seductive politician, let's put it that way.'

Robert Peston

She has been going out with current partner, Marseilles businessman Xavier Giocanti, since 2006.

An elegant dresser who favours classic skirt suits and silk scarves, Mrs Lagarde once said women make better politicians because they are less driven by 'libido and testosterone'.

Peston is married to writer and filmmaker Sian Busby. When asked for his definition of love, he once replied: 'How I feel about my wife.'

He is by no means the first high profile newsman – or indeed newswoman – to have fallen under Mrs Lagarde's spell.

The Mail's Ephraim Hardcastle column noted how Jeremy Paxman 'practically salivated as he listened to her near-perfect English' when she discussed the euro on BBC2's Newsnight in 2008.

And last year ITV News's economics editor, Daisy McAndrew, confessed to an 'embarrassing crush' on Lagarde.

Writing online, she said: 'Forgive me. For what I'm about to say will make me sound less like a hard-nosed hack and more like a gushing schoolgirl.

'Christine Lagarde rocks. She has charisma and leadership skills in buckets... she cuts a dashing figure – a shock of coiffed grey hair and extremely elegant. I say, Thank God for Madame Lagarde.'

The tongue-in-cheek animosity between Mair and Peston first surfaced when the PM host overlooked a scoop by Peston on bankers' bonuses, which led to a series of barbed exchanges before they eventually agreed to bury the hatchet.

Their Lagarde debate both delighted and offended regular listeners. 'Funniest radio moment of year,' one tweeted.

But another posted: 'Shame on Robert Peston egged on by Eddie Mair for their schoolboyish objectification of IMF leader Christine Lagarde.'

A BBC spokesman said: 'There was a light-hearted moment in the interview, but the story was still clear to our audience'.